Method of and apparatus for forming metal tubes



'F. SIEVE'RN Sept. 22,1936.

METHOD OF AND-APPARATUS FOR FORMING METAL TUBES Filed Ag. 51, 1954 lNVENTOR .ltlllllllln L- Patented Sept. 22, I936 UNITED STATES.

Fredrick Sievern, Mcl eesport, Bilassignorlof one-half to Archwonth Martin, Pittsburgh, 2a.

ApplicationAugust 31, 1934, Serial'No. 74am; 7

I t s-2 Q1? 5w My invention relates to a method ojf 'and appa ratus for forming metal tubes, and is: more "particularly applicable in connection withthebuttwelding of tubes, though it is susceptible-of employment in other ways.

;Inthemaking of butt-welded tubes difficLflty is frequently experienced in securinga joint or seam which is of such strength that it will not split n'orcrackunder crushing forces or expanding forces, and which is gas and Water tight.

Some of the weaknesses of butt-welded pipe made by the ordinary butt-welding methods :re-' suit from the presence of scale between the abutting edges of the skelp from which thetube is formed, and from thelack of properand uniform 'heatingat all points along the edges of the skelp strip. 1

My invention has for its object the provision of a means and a method whereby a more perfect seam may be secured as between the welded metal surfaces.

Some of the ways in which my invention may be practised are shown in the accompanying drawing wherein Figure 1 is a rear elevational view of a head block and welding die; Fig. 2 is a cross-sectional view thereof, and Fig. 3 is a plan view showing a modification of the structure of Fig. 1.

Referring more particularly to Figs. 1 and 2, I show a portion of a skelp bar 5 being drawn in the direction indicated by the arrow, through a forming bell 6. The tube is drawn from a furnace (not shown) through the bell, by any suitable tong mechanism or other apparatus applied to the forward end of the tube. The pulling apparatus and the bell may be of any wellknown form.

The bell is supported in a head block 1 in somewhat the usual manner, but the said head block differs from the usualtype of head block in that provision is made in connection therewith for supplying blasts of either air or combustible gas to the edges of the skelp, both before it enters the bell and at the rear-side of the bell.

The head block 1 is provided with two chambers or reservoirs 8 and 9, that are supplied with either air or gas, including combustible gases, through pipes in and II, respectively. The gaseous medium in the chamber 8 is discharged through the nozzles l2 against the edges of the skelp. The skelp is pro-heated to welding temperature in the furnace and'is drawn through the hell 6 in such manner that its edges are bent downwardly. While the skelp can be bent upwardly, if desired, I find-it preferable to bend the edges of the skelp downwardly-instead-of up wardly so that in case of excess 'soften'edor liquefied metal at the edges of the skelp, such metal will be incorporated intothe welded seam, insteadof fiow-ingaway from theseam as tends to occur w-hen the skelp' edges were bent upwardly 'The gaseous blast against the edges of the skelp, at'the-front of the bell, not only' serves to. clean said edgesg but I is usually utilized also to increase the temperature. of said tedges, thereby insuring that the edges of the skelp -will be' suificiently softened, and also producing a more uuiform .tempera'turexalong the edges of the xskelp'." The-head .blockjis' usually positioned so close to the furnace that it becomes heated to temperatures of from 600 F. to 1000 R, which is advantageous, in that the body of gas within the reservoir 8 will become heated, and make possible the heating of the edges of the skelp to higher temperatures. In case a gas of noncombustible quality is supplied, the pre-heating thereof will prevent chilling of the edges by the currents or. blasts of gas from the nozzles l2, which in that instance would serve mainly to blow scale off the edges.

The reservoir 9 is supplied with either combustible or non-combustible gases, as is the reservoir 8, and is made of sufiicient size that although it is at the rear side of the head block 1, the body of gas therein will become highly heated. The reservoir 9 will contain at all times a volume of gas which will remain in the reservoir sufficiently long to be properly heated, even though the drawing operations are continuous.

An orifice I3 is provided in the upper Wall of the reservoir 9 and so positioned that gas will be discharged against the seam of the pipe as it emerges from the bell 6. The gaseous fiow from the orifice I3 will serve to assist in incorporating molten or semi-molten metal into the seam, in cases where a relatively non-combustible gas is employed.

When a heating gas is employed, it will also effect further softening of the metal at the seam line, to thereby produce a still better seam than is secured by the use of gaseous jets at only the front side of the bell.

The top wall of the reservoir 9 is sloped, so that scale and any drops of molten metal will slide off and not accumulate at the orifice I3.

The structure as shown in Fig. 3 is substantially the same as that shown in Figs. 1 and 2',

but has an elongated slot l3 instead of a shorter slot, such as those in the ends of the nozzles l2. It will be understood that two long gas-discharging slots l3 could be employed instead of the narrower nozzles l2.

It will be obvious that the chambers 8 and. 9 need not be formed internally of the bell, but can be in the form of enlarged conduits positioned for discharge at the front and rear ends of the bell, and may be heated, when desired, in any suitable manner.

The term gaseous medium" as recited in the claims is employed in a broad sense to include air, oxygen, acetylene gas, etc.

I claim as my invention:-

1. The method of forming metal tubes, which comprises heating a tube skelp to approximately welding temperature, moving said skelp to a shaping die and simultaneously increasing the temperature of the skelp edges, passing the skelp through the die, and applying a gaseous flow to the abutting edges of the skelp in a direction perpendicular to the axis of the tube as it emerges from the die.

2. The method of forming metal tubes, which comprises heating a tube skelp to approximately welding temperature, moving said skelp to a shaping die and simultaneously increasing the temperature of the skelp edges, passing the skelp through the die, and applying a gaseous flow to the abutting edges of the skelp in an upward direction as it emerges from the die, the edges of the skelp being bent downwardly.

3. The method of forming metal tubes which comprises heating a tube skelp to welding temperature, moving said skelp to a shaping die and simultaneously applying a flow of gas under pressure to the edges of the skelp, passing the skelp through the die in a manner to bend its edges downwardly into abutting engagement, and applying a second flow of gas under pressure to the abutting edges of the skelp in an upward direction as it emerges from the die.

4. Apparatus for forming metal tubes comprising a head block, a tube-shaping die carried by said block, a conduit carried by the block, a nozzle for discharging a gas from said conduit against the edges of the skelp entering the die, a conduit carried by the rear side of said block, and means for discharging the gas from said conduit against the edges of the bent skelp as it emerges from the die, the said conduits having portions thereof enlarged so as to serve as reservoirs.

5. Apparatus for forming metal tubes, comprising a tube-shaping die adapted to be positioned adjacent to a furnace, gas conduits adjacent to the front and the rear ends of said die in position to be heated by the furnace heat, and means for directing a flow of gases from each of said conduits to the edges of the skelp as the skelp enters and leaves the die.

6. Apparatus for forming metal tubes comprising a head block, a tube shaping die carried by said block, a conduit adjacent to the block, means for discharging a gas from said conduit against the edges of the skelp entering the die, a conduit at the rear side of said block, and means for discharging the gas from said conduit against the edges of the bent skelp as it emerges from the die, the said conduits being formed unitarily with the head block.

FREDRICK SIEVERN. 

